Commercial crops are often the targets of attack by invertebrate pests such as insects. Compositions for controlling insect infestations in plants have typically been in the form of chemical insecticides. However, there are several disadvantages to using chemical insecticides. For example, chemical insecticides are generally not selective, and applications of chemical insecticides intended to control insect pests in crop plants can exert their effects on non-target insects and other invertebrates as well. Chemical insecticides often persist in the environment and can be slow to degrade, thus potentially accumulating in the food chain. Furthermore the use of persistent chemical insecticides can result in the development of resistance in the target insect species. Thus there has been a long felt need for more environmentally friendly methods for controlling or eradicating insect infestation on or in plants, i.e., methods which are species-selective, environmentally inert, non-persistent, and biodegradable, and that fit well into pest resistance management schemes.
RNA interference (RNAi, RNA-mediated gene suppression) is another approach used for pest control. In invertebrates, RNAi-based gene suppression was first demonstrated in nematodes (Fire et al., (1998) Nature, 391:806-811; Timmons & Fire (1998) Nature, 395:854). Subsequently, RNAi-based suppression of invertebrate genes using recombinant nucleic acid techniques has been reported in a number of species, including agriculturally or economically important pests from various insect and nematode taxa.
Leptinotarsa spp. form a genus including a number of species that infest commercially important plants, including many solanaceous plants (e.g., potato, tomato, eggplant, peppers, tobacco, and petunia). For example, Leptinotarsa decemlineata (Colorado potato beetle, CPB) is an early- to mid-season pest affecting solanaceous plants such as potato. Colorado potato beetles primarily feed on above-ground portions of the plant, and defoliation leads to lower tuber yields. Methods and compositions for controlling insect pests, in particular Leptinotarsa spp. which infest crop plants are desired.